Pressure distillation of heavy hydrocarbon oils



R. E. wlLsoN 1,712,187

PRESSURE DISTILLATION OF HEAVY HYDROCARBON OILS May 7, 1929.

Filed June 29, 1925 aarl ROBERT E. WILSON, OF CHICAGO, ILLINOIS, ASSIGNOR TO STANDARD OIL COMPANY, OF WRITING, INDIANA, A. CORPORATION OF INDIANA.

PRESSURE DISTILLATION 0F HEAVY HYDROCARBON OILS.

`App1icaton led June 29, 1925. Serial N0. 40,269.

The present invention relates to improvements in the pressure distillation of heavy hydrocarbon oils for the production of lighter hydrocarbon oils, such as gasoline, and will be fully understood from the-following description, illustrated by the accompanying drawings, in which apparatus for carrying the invention into effect is diagrammatically shown.

Referring to the drawings, the numeral 5 indicates the bulk supply container or drum of a still, mounted upon, but protected from the re in a furnace setting 6. From the bulk supply container the large pipes or tubes 7 and 8 depend vertically and connect respectively with upper and lower tube headers 9 and 10, between which are provided the inclined tubes 11. Suitable heating means are provided in the setting 6 for heating the tubes 11. From the container 5 a vapor pipe 13 leads to a suitable refluxing device, for example, a tower 14 which may contain plates of the bubble or other desired type. Reflux formed in the tower 14 is returned to the still lthrough pipe 15. Raw oil may be supplied through the line 12 or, if desired, may be fed directly through line 17 into the tower 14, to be preheated therein, and supplied'to the container 5, mingled with reflux, through the line 15. f

From the container 5 a discharge line 20 provided with a valve 21, leads to the intake of a suitable pump 22, illustrated diagrammatically as a surge pump. Oil thus withdrawn from the container 5 is forced by the pump 22 through line 23 into and through a pipe still or heating coil 24, fired by any suitable means. From the pipe still 24 the oil passes into a plurality of drums 25, preferably mounted in series and provided with interconnecting pipes 26 below the liquid level therein and with interconnecting pipes 27 above the level therein. vapors formed in the drums 25 pass out through vapor pipe 28 into a fractionating tower or reflux tower 29, of similar construction to the-tower 14. Condensate formed inv the tower 29 passes through valved reflux line 30 into the line 23 leading to the pipe still 24, a Suitable pump 31 being provided, if re- 'dev1ces, not shown. Similarly, a vapor line quired, for forcing the reflux into the line 23. Suitable dlscharge lines 34 are provided for the removal of oil from the drums 25.

From the tower 14 a vapor line 32 leads to suitable condensing and pressure maintaining 33 leads from the tower 29 to condensing and pressure maintaining devices.

In carrying the invention into effect, the container 5 and the associated tubes 11 and connectmg parts are partially filled with raw olltwhich 1s preferably a distillate oil having an 1n1t1al boiling point at atmospheric pressure of 500 to 550 F. The oil is gradually brought to distillation temperatures under a pressure of 4 to 6 atmospheres or higher, under whlch conditions conversion of the oil mto lighter products, including gasoline, takes place and an increase in asphaltene content of the unvaporizd liquid takes place at a progressively increasing rate. Conyerslon temperatures in excess of 700O F. are reached in the body of oil, which is heated by -its circulation through the heating pipes 11.

A fter distillation has begun, additional raw oil r1s fed into the system through the pipe 12 75 1n the desired quantities, and oil is withdrawn from the container 5 through the discharge llne' 20. The valve 21 of the discharge line 20 1s so controlled with reference to the operation of the distilling\system including the container 5, that the oil withdrawn therefrom has an asphaltene content of not over 0.4%, and preferably about 0.1%. (The asphaltenes are the constituents of the oil soluble in carbon disulfid and insoluble in petroleum ether). Thus, if the temperature of operation of the container 5 is about 7 30 F., the oil may be withdrawn therefrom through the line 20 after an average conversion period of about 10 hours, and at higher temperatures, after a correspondingly shorter period. After suitable operating conditions have been established the withdrawal of oil through the line 20 is substantially continuous, fresh oil being supplied through the line 12, also continuously, at a rate such as to `maintain a substantially constant level Within the container 5.

The oil Withdrawn from the container 5 through the line 20, preferably lagged to prevent loss of heat, is forced by a suitable pump, such as the surge pump 22 into and through the pipe still 24, in which the temperature of the partially converted oil is substantially raised, say from 100 to 150 F. and the pressure raised to 200 to 600 pounds. Thus the oil entering the pipe still or heater 24 may be at a temperature of 700 to 740 F. (the temperature prevailing in the still) and at the outlet end of the pipe still 24, the temperature of the oil may be 7 80 F. to 850 F. The rate of travel through the pipe still 24 is sufficiently rapid so that no substantial deposition of carbon from the oil takes place; some additional conversion takes place within the pipe still, but preferably not to exceed 6 or 8% on the oil passed therethrough. Ina'smuch as the oil entering the pipe still 24 is already at conversion temperatures, an eX- cessively violent heating of the oil in the pipe still is not required to bring it to the desired higher temperature. The oil which has undergone conversion tothe extent above set forth may be subjected to this treatment without substantial'deposition of carbon in the pipe heater. From the pipe still 24 the oil passes into the enlarged drums 25, which are suitably lagged,y or may be mildly heated to maintain the oil at approximately the temperature it attains in the pipe still 24, or say, not more than 50 F. less. The oil is retained in the enlarged chambers 25 for a sufficient period to permit the desired additional conversion, which may be an additonalconversion of 25 to 45%, for example. Unconverted oil is withdrawn through the lines 34, and vapors pass out of the drums 25 through the line 28 into the reflux tower 29, reflux formed therein being discharged through the line 30 and pumped by the pump 31 into the line 23 entering the pipe still 24. The pipe still 24 and chambers 25 are maintained at a substantially higher pressure than the still 5; for example, at a pressure of 200 to 600, and preferably about 400, pounds, unconverted oil being maintained substantially in liquid phase at such pressure.

Under the conditions hereinbefore set forth, a practically continuous operation of the still 5 may be conducted, without substantial depositon of carbon therein. The oil withdrawn from the container 5 is supplied at substantially .conversion temperatures to the pipe still 24 and any carbon contained therein is suspended in such a state that no substantial depositen thereof may take place in the tubes 24, providing the oil be passed through the tubes very rapidly to minimize additional cracking therein.

I claim:

1. The method of conversion of heavy hydrocarbon oils into lighter hydrocarbon oils which comprises subjecting a body of heavy distillate oil to distillation at a pressure of 4 to 6 atmospheres and at conversion temperatures, continuing such distillation until substantial conversion of the heavy oil is effected and the unvaporized oil reaches an asphaltene content not exceeding 0.4%, removing such unvaporized oil while at conversion temperature, forcing the withdrawn oil through a confined passage in a heated zone, thereby bringing its temperature to 800 F. or higher, discharging the heated oil into a conversion chamber in which no substantial decrease in temperature of the oil is permitted, and separately withdrawing vapors and unvaporized oil from said conversion chamber.

2. The method of conversion of heavy hydrocarbon oils into lighter hydrocarbon oils which comprises subjecting a body of heavy distillate oil to distillation at a pressure of at least 4 atmospheres and at conversion temperature, continuing such distillation of the heavy oil until substantial conversion thereof has been effected and the unvaporized converted oil reaches an asphaltene content not exceeding 0.4%, removing such unvaporized oil while at conversion temperature, forcing the withdrawn oil through a confined passage in a heating zone, thereby bringing its temperature up to 800 F. or higher, discharging' the heated oil into a chamber and maintaining it at conversion temperature therein to effect a further conversion thereof.

3. The method of converting heavy hydrocarbon oils into lighter hydrocarbon oil such as gasoline which comprises heating a heavy dlstillate oil under pressure to a conversion temperature for a period sufficient to form about 0.1% of asphaltene in the undistilled oil, passing the partially converted oil, substantially free from gasoline-like conversion products, through a confined passage in a heating zone, thereby increasing its temperature 100 to 150 F., and discharging the heated oil into an enlarged chamber in which vaporization takes place, and retaining the oil within said enlarged chamber to effect an adldiional conversion into gasoline-like produc s.

4. The method of converting high boiling hydrocarbon oils into lower boiling hydrocarbon oils which comprises maintaining a supply of partiallyconverted distillate oil at conversion temperature and effecting substantial conversion thereof, withdrawing therefrom oil at a rate such that the asphaltene content of the oil body does not exceed f 0.4% and forcing it through a confined passage in a heated zone without substantial deposition of carbon, its temperature being substantially raised therein, and discharging the oil into an enlarged chamber maintained at conversion temperature to effect further conversion therein, sufficient pressure being maintained within the conned passage and chamber to retain unconverted oil substantially in liquid phase.

5. The method of converting hydrocarbon oils which comprises maintaining a body of 5 oil at a cracking temperature under pressure and effecting substantial conversion thereof,

continuously withdrawing oil therefrom and continuously'supplying oil thereto to maintain the bod of oil, therate of withdrawal and supply eing such vthat the asphaltene content of the oil body does not exceed 0.4% and subjecting the withdrawn residue to further cracking before cooling.

ROBERT E. WILSON. 

